package com.lujian.casual.benchmark;

import org.openjdk.jmh.annotations.*;
import org.openjdk.jmh.infra.BenchmarkParams;
import org.openjdk.jmh.infra.ThreadParams;
import org.openjdk.jmh.runner.Runner;
import org.openjdk.jmh.runner.RunnerException;
import org.openjdk.jmh.runner.options.Options;
import org.openjdk.jmh.runner.options.OptionsBuilder;

import java.util.ArrayList;
import java.util.List;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.TimeUnit;


@BenchmarkMode(Mode.Throughput)
@OutputTimeUnit(TimeUnit.SECONDS)
@State(Scope.Benchmark)
public class BenchMarkInfraParams {


    /*
     * There is a way to query JMH about the current running mode. This is
     * possible with three infrastructure objects we can request to be injected:
     *   - BenchmarkParams: covers the benchmark-global configuration
     *   - IterationParams: covers the current iteration configuration
     *   - ThreadParams: covers the specifics about threading
     *
     * Suppose we want to check how the ConcurrentHashMap scales under different
     * parallelism levels. We can put concurrencyLevel in @Param, but it sometimes
     * inconvenient if, say, we want it to follow the @Threads count. Here is
     * how we can query JMH about how many threads was requested for the current run,
     * and put that into concurrencyLevel argument for CHM constructor.
     */

        static final int THREAD_SLICE = 1000;

        private ConcurrentHashMap<String, String> mapSingle;
        private ConcurrentHashMap<String, String> mapFollowThreads;

        @Setup
        public void setup(BenchmarkParams params) {
            int capacity = 16 * THREAD_SLICE * params.getThreads();
            mapSingle        = new ConcurrentHashMap<>(capacity, 0.75f, 1);
            mapFollowThreads = new ConcurrentHashMap<>(capacity, 0.75f, params.getThreads());
        }

    /*
     * Here is another neat trick. Generate the distinct set of keys for all threads:
     */

        @State(Scope.Thread)
        public static class Ids {
            private List<String> ids;

            @Setup
            public void setup(ThreadParams threads) {
                ids = new ArrayList<>();
                for (int c = 0; c < THREAD_SLICE; c++) {
                    ids.add("ID" + (THREAD_SLICE * threads.getThreadIndex() + c));
                }
            }
        }

        @Benchmark
        public void measureDefault(Ids ids) {
            for (String s : ids.ids) {
                mapSingle.remove(s);
                mapSingle.put(s, s);
            }
        }

        @Benchmark
        public void measureFollowThreads(Ids ids) {
            for (String s : ids.ids) {
                mapFollowThreads.remove(s);
                mapFollowThreads.put(s, s);
            }
        }

    /*
     * ============================== HOW TO RUN THIS TEST: ====================================
     *
     * You can run this test:
     *
     * a) Via the command line:
     *    $ mvn clean install
     *    $ java -jar target/benchmarks.jar JMHSample_31 -wi 5 -i 5 -t 4 -f 5
     *    (we requested 5 warmup iterations, 5 iterations, 2 threads, and 5 forks)
     *
     * b) Via the Java API:
     *    (see the JMH homepage for possible caveats when running from IDE:
     *      http://openjdk.java.net/projects/code-tools/jmh/)
     */

        public static void main(String[] args) throws RunnerException {
            Options opt = new OptionsBuilder()
                    .include(BenchMarkInfraParams.class.getSimpleName())
                    .warmupIterations(5)
                    .measurementIterations(5)
                    .threads(4)
                    .forks(5)
                    .build();

            new Runner(opt).run();
        }

}
